Without Init commands

This mode is primarily intended for external masters, which are used solely for process data transfer. The checkboxes for automatic PDO assignment and mapping in the Process Data tab must not be ticked (see section Selective PDO mapping).

Variables can then be declared on the respective terminal side. If, for example, three byte output variables are declared and the device is restarted (under TwinCAT: Reload Devices), the structure of the PD output object can be seen in the respective CoE object 0x1608. It has a length of 24 bits with three byte variables.

On the other side of the terminal, assignment and mapping should also be disabled for the data exchange, to ensure that the terminal can interpret the data and does not expect three entries with 8 bits each, but an entry with 24 bits. Moreover, the process data length on the remote side must match exactly. In this example the mapping for CoE object 0x1A01 should be disabled on the remote side (see section Symmetric PDO mapping), since otherwise a different quantity of input data is assumed and the data exchange would not work.